Which statement correctly identifies the three layers of the heart wall and their basic functions?

• A. Epicardium (visceral pericardium; protective), Myocardium (muscular layer; contracts to pump blood), Endocardium (lines chambers and valves; provides smooth lining)
• B. Endocardium (visceral pericardium; protective), Myocardium (nerve supply), Epicardium (connective tissue)
• C. Pericardium (outer sac), Myocardium (nerve), Endocardium (bone)
• D. Myocardium (outer), Endocardium (middle), Epicardium (inner)

Answer: (A)

The key concept is the three layers of the heart wall and what each does. From outside to inside, they are the epicardium, the myocardium, and the endocardium. The correct statement identifies the epicardium as the visceral pericardium that provides a protective covering. It’s the outer surface that, together with the pericardial layer, helps reduce friction as the heart beats. The myocardium is the thick muscular layer responsible for contracting to pump blood throughout the body. The endocardium lines the heart’s chambers and covers the valves, providing a smooth inner surface that minimizes friction and supports proper valve function.

The other descriptions mix up these identities: endocardium is not the visceral pericardium, and it is not the main nerve supplier or bone; epicardium is not simply connective tissue, and the layering from outside to inside cannot be myocardium–endocardium–epicardium. The accurate order and roles align with epicardium on the outside, myocardium in the middle, and endocardium on the inside, with their respective functions as described.